Heat-assisted magnetic recording head with laser diode

ABSTRACT

A heat-assisted magnetic recording head includes a slider, and an edge-emitting laser diode that emits polarized light of TM mode. The laser diode is arranged so that its bottom surface faces the top surface of the slider. An electrode of the laser diode closer to the active layer is bonded to a conductive layer of the slider, whereby the laser diode is fixed to the slider. As viewed from above the laser diode, the bottom surface of the electrode of the laser diode includes a first area that a light propagation path of the laser diode overlies, and a second area other than the first area. The top surface of the conductive layer is in contact not with the first area but with the second area of the bottom surface of the electrode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat-assisted magnetic recording headfor use in heat-assisted magnetic recording where a magnetic recordingmedium is irradiated with near-field light to lower the coercivity ofthe magnetic recording medium for data recording, a method ofmanufacturing the same, and a head gimbal assembly and a magneticrecording device each of which includes the heat-assisted magneticrecording head.

2. Description of the Related Art

Recently, magnetic recording devices such as a magnetic disk drive havebeen improved in recording density, and thin-film magnetic heads andmagnetic recording media of improved performance have been demandedaccordingly. Among the thin-film magnetic heads, a composite thin-filmmagnetic head has been used widely. The composite thin-film magnetichead has such a structure that a reproducing head including amagnetoresistive element (hereinafter, also referred to as MR element)intended for reading and a recording head including an induction-typeelectromagnetic transducer intended for writing are stacked on asubstrate. In a magnetic disk drive, the thin-film magnetic head ismounted on a slider that flies slightly above the surface of themagnetic recording medium.

Magnetic recording media are discrete media each made of an aggregate ofmagnetic fine particles, each magnetic fine particle forming asingle-domain structure. A single recording bit of a magnetic recordingmedium is composed of a plurality of magnetic fine particles. Forimproved recording density, it is necessary to reduce asperities at theborders between adjoining recording bits. To achieve this, the magneticfine particles must be made smaller. However, making the magnetic fineparticles smaller causes the problem that the thermal stability ofmagnetization of the magnetic fine particles decreases with decreasingvolume of the magnetic fine particles. To solve this problem, it iseffective to increase the anisotropic energy of the magnetic fineparticles. However, increasing the anisotropic energy of the magneticfine particles leads to an increase in coercivity of the magneticrecording medium, and this makes it difficult to perform data recordingwith existing magnetic heads.

To solve the foregoing problems, there has been proposed a techniqueso-called heat-assisted magnetic recording. This technique uses amagnetic recording medium having high coercivity. When recording data, amagnetic field and heat are simultaneously applied to the area of themagnetic recording medium where to record data, so that the area risesin temperature and drops in coercivity for data recording. Hereinafter,a magnetic head for use in heat-assisted magnetic recording will bereferred to as a heat-assisted magnetic recording head.

In heat-assisted magnetic recording, near-field light is typically usedas a means for applying heat to the magnetic recording medium. Acommonly known method for generating near-field light is to use anear-field optical probe or so-called plasmon antenna, which is a pieceof metal that generates near-field light from plasmons excited byirradiation with light.

However, a plasmon antenna that is directly irradiated with light togenerate near-field light is known to exhibit very low efficiency ofconversion of the applied light into near-field light. The energy of thelight applied to the plasmon antenna is mostly reflected off the surfaceof the plasmon antenna, or converted into thermal energy and absorbed bythe plasmon antenna. The plasmon antenna is small in volume since thesize of the plasmon antenna is set to be smaller than or equal to thewavelength of the light. The plasmon antenna therefore shows asignificant increase in temperature when it absorbes the thermal energy.

Such a temperature increase makes the plasmon antenna expand in volumeand protrude from a medium facing surface, which is the surface of theheat-assisted magnetic recording head to face the magnetic recordingmedium. This causes an end of the reproducing head located in the mediumfacing surface to get farther from the magnetic recording medium,thereby causing the problem that a servo signal cannot be read duringrecording operations.

To cope with this, as described in, for example, U.S. Pat. No.7,330,404, there has been proposed a technique in which lightpropagating through a waveguide is not directly applied to a plasmonantenna but is coupled with a near-field light generating element via abuffer layer in a surface plasmon polariton mode to thereby excitesurface plasmons on the near field light generating element. Thenear-field light generating element has a near-field light generatingpart that is located in the medium facing surface and generatesnear-field light. According to this technique, the light propagatingthrough the waveguide is totally reflected at the interface between thewaveguide and the buffer layer to generate evanescent light permeatinginto the buffer layer. The evanescent light and collective oscillationsof charges on the near-field light generating element, i.e., surfaceplasmons, are coupled with each other to excite the surface plasmons onthe near-field light generating element. In the near-field lightgenerating element, the excited surface plasmons propagate to thenear-field light generating part, and near-field light occurs from thenear-field light generating part. According to this technique, since thenear-field light generating element is not directly irradiated with thelight propagating through the waveguide, it is possible to prevent anexcessive increase in temperature of the near-field light generatingelement.

In a near-field light generating device including the waveguide, thebuffer layer and the near-field light generating element, a possiblelayout of the waveguide, the buffer layer and the near-field lightgenerating element is such that the near-field light generating elementis opposed to the top or bottom surface of the waveguide with the bufferlayer interposed therebetween in the vicinity of the medium facingsurface. The waveguide allows propagation of laser light to be used forgenerating near-field light. In order to generate surface plasmons ofhigh intensity on the near-field light generating element, the foregoinglayout requires that the laser light to propagate through the waveguidebe TM-polarized light whose electric field oscillates in a directionperpendicular to the top and bottom surfaces of the waveguide.

Possible techniques of placement of a light source that emits the laserlight to propagate through the waveguide are broadly classified into thefollowing two. A first technique is to place the light source away fromthe slider. A second technique is to fix the light source to the slider.

The first technique is described in JP 2007-200475 A, for example. Thesecond technique is described in U.S. Patent Application Publication No.2008/0002298 A1 and U.S. Patent Application Publication No. 2008/0043360A1, for example.

The first technique requires an optical path of extended lengthincluding such optical elements as a mirror, lens, and optical fiber inorder to guide the light from the light source to the waveguide. Thiscauses the problem of increasing energy loss of the light in the path.The second technique is free from the foregoing problem since theoptical path for guiding the light from the light source to thewaveguide is short.

The second technique, however, has the following problem. Hereinafter,the problem that can occur with the second technique will be describedin detail. The second technique typically uses a laser diode as thelight source. The laser diodes available include edge-emitting laserdiodes and surface-emitting laser diodes. In an edge-emitting laserdiode, the emission part for emitting the laser light is located in anend face that lies at an end of the laser diode in a direction parallelto the plane of an active layer. The emission part emits the laser lightin the direction parallel to the plane of the active layer. In asurface-emitting laser diode, the emission part for emitting the laserlight is located in a surface that lies at an end of the laser diode ina direction perpendicular to the plane of the active layer. The emissionpart emits the laser light in the direction perpendicular to the planeof the active layer.

The laser light emitted from a laser diode can be made incident on thewaveguide by a technique described in U.S. Patent ApplicationPublication No. 2008/0002298 A1, for example. This publication describesarranging a surface-emitting laser diode with its emission part opposedto the surface of the slider on the trailing side so that the laserlight emitted from the emission part is incident on the waveguide fromabove. Surface-emitting laser diodes, however, typically have a loweroptical output as compared with edge-emitting laser diodes. Thetechnique therefore has the problem that it is difficult to providelaser light of sufficiently high intensity for use in generatingnear-field light.

The laser light emitted from a laser diode may be made incident on thewaveguide by other techniques. For example, U.S. Patent ApplicationPublication No. 2008/0043360 A1 describes a technique in which theincident end face of the waveguide is arranged at the surface oppositeto the medium facing surface of the slider, and the laser diode isarranged with its emission part opposed to this incident end face sothat the laser light emitted from the emission part is incident on theincident end face of the waveguide without the intervention of anyoptical element. This technique allows the use of an edge-emitting laserdiode which has a high optical output. However, this technique has theproblem that it is difficult to align the emission part of the laserdiode with respect to the incident end face of the waveguide with highprecision, since the position of the emission part of the laser diodecan vary within a plane perpendicular to the optical axis of thewaveguide.

To cope with this, the edge-emitting laser diode may be fixed to the topsurface of the slider that lies at an end of the slider above the topsurface of the substrate, so that the laser light is emitted in adirection parallel to the top surface of the slider, while arranging thewaveguide so that the incident end face of the waveguide is opposed tothe emission part of the laser diode.

An edge-emitting laser diode typically includes: an n-substrate havingtwo surfaces that face toward mutually opposite directions; ann-electrode bonded to one of the two surfaces of the n-substrate; alaser structure part integrated on the other of the two surfaces of then-substrate; and a p-electrode bonded to the laser structure part suchthat the laser structure part is sandwiched between the n-substrate andthe p-electrode. The laser structure part includes the active layer. Theedge-emitting laser diode has two surfaces that lie at opposite ends inthe direction perpendicular to the plane of the active layer; one isformed by the surface of the n-electrode, and the other is formed by thesurface of the p-electrode. The distance between the surface of thep-electrode and the active layer is smaller than the distance betweenthe surface of the n-electrode and the active layer. When theedge-emitting laser diode is fixed to the top surface of the slider asmentioned above, the laser diode is preferably arranged so that thesurface of the p-electrode closer to the active layer faces the topsurface of the slider, rather than so that the surface of then-electrode faces the top surface of the slider. The reason is that theformer arrangement can reduce the difference in level between the bottomsurface of the laser diode and the position of the incident end face ofthe waveguide. One of possible methods for fixing the edge-emittinglaser diode to the slider so that the surface of the p-electrode facesthe top surface of the slider is to solder-bond the p-electrode of thelaser diode to a conductive layer that is disposed on the top surface ofthe slider.

Now, let us consider a configuration in which the edge-emitting laserdiode is fixed to the slider so that the surface of the p-electrodefaces the top surface of the slider, and the waveguide is arranged sothat the incident end face of the waveguide is opposed to the emissionpart of the laser diode as described above. Here, suppose also that thenear-field light generating element is arranged in the vicinity of themedium facing surface so that the near-field light generating element isopposed to the top surface or the bottom surface of the waveguide withthe buffer layer interposed therebetween, as mentioned previously. Thisconfiguration requires that the laser light to propagate through thewaveguide be TM-polarized light as mentioned previously. It is thereforenecessary to use an edge-emitting laser diode that emits polarized lightof TM mode whose electric field oscillates in the directionperpendicular to the plane of the active layer. Such a configuration hasthe following problem.

A laser diode that emits polarized light of TM mode is typicallyachieved by a strained quantum well structure in which the active layeris given a tensile strain. In the case of the laser diode that emitspolarized light of TM mode, the state of polarization of the emittedlight changes more sensitively in response to the stress on the activelayer than in the case of a laser diode that emits polarized light of TEmode whose electric field oscillates in the direction parallel to theplane of the active layer. Consequently, if the p-electrode of the laserdiode that emits polarized light of TM mode is solder-bonded to theconductive layer disposed on the top surface of the slider, a stressoccurring from the solidification of the solder may act on the activelayer located near the p-electrode to change the state of polarizationof the emitted light.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a heat-assistedmagnetic recording head including an edge-emitting laser diode thatemits polarized light of TM mode, wherein the laser diode is arrangedwith its bottom surface toward the top surface of the slider and isfixed to the slider by bonding an electrode of the laser diode to aconductive layer of the slider, the heat-assisted magnetic recordinghead being capable of suppressing changes in the state of polarizationof light emitted from the laser diode, and to provide a manufacturingmethod for the heat-assisted magnetic recording head, and a head gimbalassembly and a magnetic recording device each of which includes theheat-assisted magnetic recording head.

A heat-assisted magnetic recording head according to the presentinvention includes a slider, and an edge-emitting laser diode fixed tothe slider. The slider includes: a medium facing surface that faces amagnetic recording medium; a magnetic pole that has an end face locatedin the medium facing surface and produces a recording magnetic field forrecording data on the magnetic recording medium; a waveguide that allowslight to propagate therethrough; a near-field light generating elementthat generates near-field light; and a substrate on which the magneticpole, the near-field light generating element and the waveguide arestacked. The substrate has a top surface facing toward the magneticpole, the near-field light generating element and the waveguide. Theslider has a top surface that lies at an end above the top surface ofthe substrate.

The laser diode includes: an active layer; an emitting end face thatlies at an end in a direction parallel to a plane of the active layerand includes an emission part for emitting laser light; a lightpropagation path that includes a part of the active layer and extends ina direction perpendicular to the emitting end face; a bottom surface anda top surface that lie at opposite ends in a direction perpendicular tothe plane of the active layer; and an electrode having a bottom surfacethat constitutes at least a part of the bottom surface of the laserdiode. The laser diode is arranged so that the bottom surface of thelaser diode faces the top surface of the slider. The light propagationpath has a width smaller than that of the laser diode in a directionparallel to the emitting end face and the plane of the active layer. Adistance between the bottom surface of the laser diode and the activelayer is smaller than that between the top surface of the laser diodeand the active layer. The laser light emitted from the emission part ispolarized light of TM mode whose electric field oscillates in thedirection perpendicular to the plane of the active layer.

The waveguide has an outer surface. The outer surface includes anincident end face that is opposed to the emission part of the laserdiode. The near-field light generating element has a near-field lightgenerating part that is located in the medium facing surface, and acoupling part that is opposed to the outer surface of the waveguide. Asurface plasmon is excited on the coupling part based on the lightpropagating through the waveguide. The surface plasmon propagates to thenear-field light generating part, and the near-field light generatingpart generates near-field light based on the surface plasmon.

The slider further includes a conductive layer having a top surface thatconstitutes a part of the top surface of the slider. The electrode ofthe laser diode is bonded to the conductive layer of the slider. Asviewed from above the laser diode, the bottom surface of the electrodeof the laser diode includes a first area that the light propagation pathoverlies, and a second area other than the first area. The top surfaceof the conductive layer is in contact not with the first area but withthe second area of the bottom surface of the electrode. Consequently,according to the present invention, it is possible to prevent a stressresulting from the bonding between the electrode of the laser diode andthe conductive layer of the slider from acting on the light propagationpath.

A manufacturing method for the heat-assisted magnetic recording headaccording to the present invention includes the steps of fabricating theslider; and fixing the laser diode to the slider. In the step of fixingthe laser diode to the slider, the electrode of the laser diode isbonded to the conductive layer of the slider by ultrasonic bondingwherein ultrasonic vibrations are applied to the laser diode in thedirection perpendicular to the emitting end face, with the second areaof the bottom surface of the electrode in contact with the top surfaceof the conductive layer. According to the present invention, it ispossible to reduce the stress that results from the bonding between theelectrode of the laser diode and the conductive layer of the slider, ascompared with the case where the electrode is bonded to the conductivelayer by soldering. In this respect also, the present invention makes itpossible to prevent the stress resulting from the bonding between theelectrode of the laser diode and the conductive layer of the slider fromacting on the light propagation path. Furthermore, according to thepresent invention, since ultrasonic vibrations are applied to the laserdiode in the direction perpendicular to the emitting end face inultrasonic bonding, it is possible to prevent the emission part of thelaser diode from being misaligned with respect to the incident end faceof the waveguide in a direction parallel to the emitting end face.

In the heat-assisted magnetic recording head or the manufacturing methodfor the same according to the present invention, the second area mayinclude two portions that sandwich the first area therebetween. The topsurface of the conductive layer may include a first contact surface anda second contact surface that make contact with the two portions of thesecond area. In this case, the conductive layer may have a first portionhaving the first contact surface and a second portion having the secondcontact surface, the first and second portions being separated from eachother. Alternatively, the slider may include an insulating layerdisposed under the conductive layer. The insulating layer may have a topsurface, and the top surface of the insulating layer may have a recessthat is opposed to the first area of the bottom surface of theelectrode. In this case, the conductive layer may include a portion thatis recessed along the recess of the top surface of the insulating layerso as not to make contact with the first area.

In the heat-assisted magnetic recording head or the manufacturing methodfor the same according to the present invention, the slider may furtherinclude a buffer layer that has a refractive index lower than that ofthe waveguide and is interposed between the coupling part and the outersurface of the waveguide. In this case, a surface plasmon is excited onthe coupling part through coupling with evanescent light that occursfrom the interface between the waveguide and the buffer layer.

In the heat-assisted magnetic recording head or the manufacturing methodfor the same according to the present invention, each of the electrodeand the conductive layer may be made of a metal that contains Au as amain component. As employed herein, “a main component” refers to acomponent that occupies 50 atomic % or more of the whole.

In the heat-assisted magnetic recording head or the manufacturing methodfor the same according to the present invention, the emitting end faceof the laser diode may be positioned to leave a gap from the incidentend face of the waveguide.

A head gimbal assembly according to the present invention includes: theheat-assisted magnetic recording head according to the presentinvention; and a suspension that supports the heat-assisted magneticrecording head. A magnetic recording device according to the presentinvention includes: a magnetic recording medium; the heat-assistedmagnetic recording head according to the present invention; and apositioning device that supports the heat-assisted magnetic recordinghead and positions the same with respect to the magnetic recordingmedium.

In the heat-assisted magnetic recording head, the head gimbal assemblyor the magnetic recording device of the present invention, theedge-emitting laser diode that emits polarized light of TM mode isarranged so that its bottom surface faces the top surface of the slider,and the laser diode is fixed to the slider by bonding the electrode ofthe laser diode to the conductive layer of the slider. In the presentinvention, as viewed from above the laser diode, the bottom surface ofthe electrode of the laser diode includes the first area that the lightpropagation path of the laser diode overlies, and the second area otherthan the first area. The top surface of the conductive layer is incontact not with the first area but with the second area of the bottomsurface of the electrode. According to the present invention, it is thuspossible to prevent a stress resulting from the bonding between theelectrode of the laser diode and the conductive layer of the slider fromacting on the light propagation path. Consequently, the presentinvention makes it possible to suppress changes in the state ofpolarization of the light emitted from the laser diode.

In the manufacturing method for the heat-assisted magnetic recordinghead of the present invention, the electrode of the laser diode isbonded to the conductive layer of the slider by ultrasonic bondingwherein ultrasonic vibrations are applied to the laser diode in thedirection perpendicular to the emitting end face, with the second areaof the bottom surface of the electrode in contact with the top surfaceof the conductive layer. In addition to providing the foregoing effectsof the heat-assisted magnetic recording head, the manufacturing methodof the present invention thus makes it possible to prevent the emissionpart of the laser diode from being misaligned with respect the incidentend face of the waveguide in a direction parallel to the emitting endface. Consequently, according to the present invention, it is possibleto prevent a drop in intensity of the laser light to be used forgenerating near-field light.

Other and further objects, features and advantages of the presentinvention will appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a conductive layer of a slider anda laser diode in a heat-assisted magnetic recording head according to afirst embodiment of the invention.

FIG. 2 is an explanatory diagram for explaining the step of fixing thelaser diode to the slider in a manufacturing method for theheat-assisted magnetic recording head according to the first embodimentof the invention.

FIG. 3 is an explanatory diagram showing the layout of the main part ofthe heat-assisted magnetic recording head according to the firstembodiment of the invention.

FIG. 4 is a perspective view of the main part of the heat-assistedmagnetic recording head according to the first embodiment of theinvention.

FIG. 5 is a cross-sectional view showing a part of the heat-assistedmagnetic recording head taken along line 5-5 of FIG. 3.

FIG. 6 is a cross-sectional view showing a part of the heat-assistedmagnetic recording head taken along line 6-6 of FIG. 3.

FIG. 7 is a perspective view showing the laser diode of the firstembodiment of the invention.

FIG. 8 is a perspective view showing a magnetic recording deviceaccording to the first embodiment of the invention.

FIG. 9 is a perspective view showing a head gimbal assembly according tothe first embodiment of the invention.

FIG. 10 is an explanatory diagram showing the general configuration ofthe heat-assisted magnetic recording head according to the firstembodiment of the invention.

FIG. 11 is a perspective view showing the waveguide, the buffer layerand the near-field light generating element of the heat-assistedmagnetic recording head according to the first embodiment of theinvention.

FIG. 12 is an explanatory diagram for explaining the principle ofgeneration of near-field light by the heat-assisted magnetic recordinghead according to the first embodiment of the invention.

FIG. 13 is a block diagram showing the circuit configuration of themagnetic recording device according to the first embodiment of theinvention.

FIG. 14 is an explanatory diagram showing a step in the manufacturingprocess of the heat-assisted magnetic recording head according to thefirst embodiment of the invention.

FIG. 15 is an explanatory diagram showing a step that follows the stepof FIG. 14.

FIG. 16 is an explanatory diagram showing a step that follows the stepof FIG. 15.

FIG. 17 is an explanatory diagram showing a step that follows the stepof FIG. 16.

FIG. 18 is an explanatory diagram showing a step that follows the stepof FIG. 17.

FIG. 19 is an explanatory diagram showing a step that follows the stepof FIG. 18.

FIG. 20 is an explanatory diagram showing a step that follows the stepof FIG. 19.

FIG. 21 is an explanatory diagram showing a step that follows the stepof FIG. 20.

FIG. 22 is an explanatory diagram showing a step that follows the stepof FIG. 21.

FIG. 23 is an explanatory diagram showing a step that follows the stepof FIG. 22.

FIG. 24 is an explanatory diagram showing a step that follows the stepof FIG. 23.

FIG. 25 is a cross-sectional view showing a part of a heat-assistedmagnetic recording head according to a second embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Preferred embodiments of the present invention will now be described indetail with reference to the drawings. Reference is first made to FIG. 8to describe a magnetic disk drive as a magnetic recording deviceaccording to a first embodiment of the invention. As shown in FIG. 8,the magnetic disk drive includes a plurality of magnetic disks 201 as aplurality of magnetic recording media, and a spindle motor 202 forrotating the plurality of magnetic disks 201. The magnetic disks 201 ofthe present embodiment are for use in perpendicular magnetic recording.Each magnetic disk 201 has such a structure that a soft magnetic backinglayer, a middle layer and a magnetic recording layer (perpendicularmagnetization layer) are stacked in this order on a disk substrate.

The magnetic disk drive further includes an assembly carriage device 210having a plurality of driving arms 211, and a plurality of head gimbalassemblies 212 attached to respective distal ends of the driving arms211. Each head gimbal assembly 212 includes a heat-assisted magneticrecording head 1 according to the present embodiment, and a suspension220 that supports the heat-assisted magnetic recording head 1.

The assembly carriage device 210 is a device for positioning eachheat-assisted magnetic recording head 1 on tracks that are formed in themagnetic recording layer of each magnetic disk 201 and that haverecording bits aligned thereon. The assembly carriage device 210 furtherhas a pivot bearing shaft 213 and a voice coil motor 214. The pluralityof driving arms 211 are stacked in a direction along the pivot bearingshaft 213 and are pivotable about the shaft 213 by being driven by thevoice coil motor 214. The magnetic recording device according to thepresent invention is not structurally limited to the magnetic disk drivehaving the above-described configuration. For example, the magneticrecording device according to the present invention may be provided witha single magnetic disk 201, a single driving arm 211, a single headgimbal assembly 212 and a single heat-assisted magnetic recording head1.

The magnetic disk drive further includes a control circuit 230 forcontrolling the recording and reproducing operations of theheat-assisted magnetic recording heads 1 and also for controlling thelight emitting operation of a laser diode serving as a light source forgenerating laser light for heat-assisted magnetic recording describedlater.

FIG. 9 is a perspective view of the head gimbal assembly 212 of FIG. 8.As previously described, the head gimbal assembly 212 includes theheat-assisted magnetic recording head 1 and the suspension 220. Thesuspension 220 has a load beam 221, a flexure 222 fixed to the load beam221 and having flexibility, a base plate 223 provided at the base partof the load beam 221, and a wiring member 224 provided on the load beam221 and the flexure 222. The wiring member 224 includes a plurality ofleads. The heat-assisted magnetic recording head 1 is fixed to theflexture 222 at the distal end of the suspension 220 such that the head1 faces the surface of the magnetic disk 201 with a predeterminedspacing (flying height). One end of the wiring member 224 iselectrically connected to a plurality of terminals of the heat-assistedmagnetic recording head 1. The other end of the wiring member 224 isprovided with a plurality of pad-shaped terminals arranged at the basepart of the load beam 221.

The assembly carriage device 210 and the suspension 220 correspond tothe positioning device according to the present invention. The headgimbal assembly according to the present invention is not limited to theone having the configuration shown in FIG. 9. For example, the headgimbal assembly according to the present invention may have an IC chipfor driving the head that is mounted somewhere along the suspension 220.

The heat-assisted magnetic recording head 1 according to the presentembodiment will now be described in detail. As shown in FIG. 9, theheat-assisted magnetic recording head 1 includes a slider 10, and anedge-emitting laser diode 60 fixed to the slider 10. The slider 10 isnearly hexahedron-shaped, and has a medium facing surface 10 a thatfaces the magnetic recording medium, a rear surface 10 b opposite to themedium facing surface 10 a, and four surfaces that connect the mediumfacing surface 10 a to the rear surface 10 b.

FIG. 3 is an explanatory diagram showing the layout of the main part ofthe heat-assisted magnetic recording head 1. FIG. 4 is a perspectiveview of the main part of the heat-assisted magnetic recording head 1.FIG. 5 is a cross-sectional view showing a part of the heat-assistedmagnetic recording head 1 taken along line 5-5 of FIG. 3. FIG. 6 is across-sectional view showing a part of the heat-assisted magneticrecording head 1 taken along line 6-6 of FIG. 3.

As shown in FIG. 4, the slider 10 includes a substrate 11 and a headunit 12. The substrate 11 is rectangular-solid-shaped and is made of aceramic material such as aluminum oxide-titanium carbide (Al₂O₃—TiC).The substrate 11 has a top surface 11 c. The top surface 11 c isperpendicular to the medium facing surface 10 a. The head unit 12 isintegrated on the top surface 11 c of the substrate 11. The mediumfacing surface 10 a is processed so as to obtain an appropriate flyingheight of the slider 10 with respect to the magnetic disk 201. Theslider 10 has a top surface 10 c that lies at an end above the topsurface 11 c of the substrate 11. The top surface 10 c is one of thefour surfaces of the slider 10 that connect the medium facing surface 10a to the rear surface 10 b. FIG. 4 shows the heat-assisted magneticrecording head 1 placed so that the top surface 10 c faces toward theviewer. In FIG. 3, some of the components of the head unit 12 located atlevels lower than the top surface 10 c are drawn in solid lines for thesake of convenience.

Where the components of the head unit 12 and the laser diode 60 areconcerned, with respect to a reference position, a position located in adirection that is perpendicular to the top surface 11 c of the substrate11 and gets away from the top surface 11 c is defined as “above”,whereas a position located in a direction opposite to the foregoingdirection is defined as “below”. Where the components of the head unit12 and the laser diode 60 are concerned, the surface closer to the topsurface 11 c is defined as a “bottom surface,” and the surface fartherfrom the top surface 11 c as a “top surface”.

Moreover, X direction, Y direction, Z direction, −X direction, −Ydirection and −Z direction will be defined as follows. The X directionis a direction perpendicular to the medium facing surface 10 a andheading from the medium facing surface 10 a toward the rear surface 10b. The Y direction is a direction parallel to the medium facing surface10 a and the top surface 11 c of the substrate 11 and heading toward theright in FIG. 4. The Z direction is a direction perpendicular to the topsurface 11 c of the substrate 11 and getting away from the top surface11 c. The −X direction, the −Y direction and the −Z direction areopposite to the X direction, the Y direction and the Z direction,respectively. As viewed from the slider 10, the magnetic disk 201 movesin the Z direction. The slider 10 has an air inflow end (a leading end)at the end of the medium facing surface 10 a in the −Z direction. Theslider 10 has an air outflow end (a trailing end) at the end of themedium facing surface 10 a in the Z direction. A track width directionis a direction parallel to the Y direction.

As shown in FIG. 4, the head unit 12 includes an overcoat layer 50 whichis an uppermost layer of the head unit 12. The overcoat layer 50 isprovided to cover a part of the top surface of the head unit 12excluding the overcoat layer 50. Thus, as shown in FIG. 5 and FIG. 6,the top surface 10 c of the slider 10 has a first portion 10 c 1 that isnot covered with the overcoat layer 50, and a second portion 10 c 2 thatis formed by the top surface of the overcoat layer 50. The secondportion 10 c 2 is located farther from the top surface 11 c of thesubstrate 11 than is the first portion 10 c 1. The laser diode 60 isdisposed on the first portion 10 c 1.

The head unit 12 further includes a plurality of pad-shaped terminalsarranged on the top surface of the overcoat layer 50. FIG. 3 and FIG. 4show an example in which the head unit 12 has eight terminals 51A, 51B,52A, 52B, 53A, 53B, 54A, and 54B. For the sake of convenience, FIG. 5shows the terminal 54B in a position different from the actual position.

FIG. 10 is an explanatory diagram showing the general configuration ofthe heat-assisted magnetic recording head 1. For the sake ofconvenience, FIG. 10 shows some of the components of the head unit 12 inshapes and layout different from those in the actual configuration. TheX, Y, and Z directions shown in FIG. 10 apply only to the vicinity ofthe medium facing surface 10 a.

As shown in FIG. 10, the head unit 12 includes an insulating layer 13disposed on the top surface 11 c of the substrate 11, and a reproducinghead 14 and a recording head 15 that are stacked on the insulating layer13 in this order. The insulating layer 13 is made of an insulatingmaterial such as Al₂O₃ (hereinafter, also referred to as alumina).

The reproducing head 14 includes: a lower shield layer 21 disposed onthe insulating layer 13; an MR element 22 disposed on the lower shieldlayer 21; an upper shield layer 23 disposed on the MR element 22; and aninsulating layer 24 disposed around the MR element 22 between the lowershield layer 21 and the upper shield layer 23. The lower shield layer 21and the upper shield layer 23 are each made of a soft magnetic material.The insulating layer 24 is made of an insulating material such asalumina.

An end of the MR element 22 is located in the medium facing surface 10a. The MR element may be a giant magnetoresistive (GMR) element or atunneling magnetoresistive (TMR) element, for example. The GMR elementmay be of either the current-in-plane (CIP) type in which a sensecurrent for magnetic signal detection is fed in a direction nearlyparallel to the plane of layers constituting the GMR element or thecurrent-perpendicular-to-plane (CPP) type in which the sense current isfed in a direction nearly perpendicular to the plane of layersconstituting the GMR element.

If the MR element 22 is a TMR element or a CPP-type GMR element, thelower shield layer 21 and the upper shield layer 23 may also function aselectrodes for feeding the sense current to the MR element 22. FIG. 10shows an example in which the MR element 22 is a TMR element or aCPP-type GMR element. In this example, the head unit 12 furtherincludes: a wiring layer 16A having an end electrically connected to thelower shield layer 21; a wiring layer 16B having an end electricallyconnected to the upper shield layer 23; a connecting part 17A thatelectrically connects the other end of the wiring layer 16A to theterminal 51A; and a connecting part 17B that electrically connects theother end of the wiring layer 16B to the terminal 51B. The wiring layers16A and 16B and the connecting parts 17A and 17B are each made of aconductive material such as Cu. Each of the connecting parts 17A and 17Bis formed by stacking a plurality of conductor layers of columnar shape.

If the MR element 22 is a CIP-type GMR element, insulating films arerespectively provided between the MR element 22 and the lower shieldlayer 21 and between the MR element 22 and the upper shield layer 23,and two wiring layers for feeding the sense current to the MR element 22are provided between these insulating films.

The head unit 12 further includes: an insulating layer 25 disposed onthe upper shield layer 23; a middle shield layer 26 disposed on theinsulating layer 25; and an insulating layer 27 disposed on the middleshield layer 26. The middle shield layer 26 has the function ofshielding the MR element 22 from a magnetic field produced in therecording head 15. The insulating layers 25 and 27 are each made of aninsulating material such as alumina. The middle shield layer 26 is madeof a soft magnetic material. The insulating layer 25 and the middleshield layer 26 may be omitted.

The recording head 15 of the present embodiment is for use inperpendicular magnetic recording. The recording head 15 includes: alower coil 31 disposed on the insulating layer 27; an insulating layer32 covering the lower coil 31; a return magnetic pole layer 33 disposedon the insulating layer 32; and an insulating layer 34 disposed aroundthe return magnetic pole layer 33 on the insulating layer 32. Therecording head 15 further includes: a coupling layer 35 disposed on apart of the return magnetic pole layer 33 away from the medium facingsurface 10 a; an insulating layer 36 disposed around the coupling layer35 on the return magnetic pole layer 33 and the insulating layer 34; anupper coil 37 disposed on the insulating layer 36; and an insulatinglayer 38 covering the upper coil 37. The top surface of the couplinglayer 35 is exposed in the top surface of the insulating layer 38.

The recording head 15 further includes a yoke layer 39 disposed over thecoupling layer 35 and the insulating layer 38; an insulating layer 40disposed around the yoke layer 39 on the insulating layer 38; a magneticpole 41 disposed on the yoke layer 39 and the insulating layer 40; andan insulating layer 42 disposed around the magnetic pole 41 on the yokelayer 39 and the insulating layer 40.

Each of the lower coil 31 and the upper coil 37 is made of a conductivematerial such as Cu. Each of the return magnetic pole layer 33, thecoupling layer 35, the yoke layer 39 and the magnetic pole 41 is made ofa soft magnetic material. Each of the insulating layers 32, 34, 36, 38,40 and 42 is made of an insulating material such as alumina.

The lower coil 31 and the upper coil 37 are each planar spiral-shaped.The upper coil 37 is wound around the coupling layer 35. The inner endof the winding of the upper coil 37 is electrically connected to theinner end of the winding of the lower coil 31 through a not-shownconnecting layer of columnar shape that penetrates through theinsulating layers 36, 34 and 32. The lower coil 31 and the upper coil 37are thereby connected in series. The lower coil 31 and the upper coil 37are wound in the same direction of rotation from the outer end to theinner end. When an electric current is supplied to the lower coil 31 andthe upper coil 37, the lower coil 31 and the upper coil 37 thus producemagnetic fields in opposite directions at their respective centers. Theupper coil 37 produces a magnetic field corresponding to data to berecorded on the magnetic disk 201. The lower coil 31 produces a magneticfield that prevents the magnetic field produced by the upper coil 37from affecting the reproducing head 14.

The recording head 15 further includes: a connecting layer 28 ofcolumnar shape, with its bottom end electrically connected to the outerend of the lower coil 31; a wiring layer 29A having an end electricallyconnected to the top end of the connecting layer 28; a wiring layer 29Bhaving an end electrically connected to the outer end of the upper coil37; a connecting part 30A that electrically connects the other end ofthe wiring layer 29A to the terminal 53A; and a connecting part 30B thatelectrically connects the other end of the wiring layer 29B to theterminal 53B. The connecting layer 28, the wiring layers 29A and 29B,and the connecting parts 30A and 30B are each made of a conductivematerial such as Cu. Each of the connecting parts 30A and 30B is formedby stacking a plurality of conductor layers of columnar shape.

Each of the return magnetic pole layer 33 and the magnetic pole 41 hasan end face located in the medium facing surface 10 a. The yoke layer 39has an end face that is closer to the medium facing surface 10 a, andthis end face is located at a distance from the medium facing surface 10a. The coupling layer 35 couples the return magnetic pole layer 33 andthe yoke layer 39 to each other at a position away from the mediumfacing surface 10 a. The return magnetic pole layer 33, the couplinglayer 35, the yoke layer 39 and the magnetic pole 41 form a magneticpath for passing a magnetic flux corresponding to the magnetic fieldproduced by the upper coil 37. The magnetic pole 41 produces a recordingmagnetic field for recording data on the magnetic disk 201 by means ofthe perpendicular magnetic recording system. The return magnetic polelayer 33 returns a magnetic flux that has been generated from themagnetic pole 41 and has magnetized the magnetic disk 201.

The recording head 15 further includes: an insulating layer 43 disposedover the magnetic pole 41 and the insulating layer 42; a near-fieldlight generating element 44 disposed on the insulating layer 43; and aninsulating layer 45 disposed around the near-field light generatingelement 44 on the insulating layer 43. The recording head 15 furtherincludes: a buffer layer 46 disposed over the near-field lightgenerating element 44 and the insulating layer 45; and a waveguide 47disposed on the buffer layer 46.

The insulating layers 43 and 45 are each made of an insulating materialsuch as alumina. The near-field light generating element 44 is made of aconductive material such as metal. For example, the near-field lightgenerating element 44 may be made of one element selected from the groupconsisting of Pd, Pt, Rh, Ir, Ru, Au, Ag, Cu and Al, or an alloycomposed of two or more of these elements.

The waveguide 47 is made of a dielectric material that transmits laserlight emitted by the laser diode 60. The waveguide 47 has an outersurface. The outer surface includes an incident end face 47 a, and anend face 47 b that is closer to the medium facing surface 10 a. WhileFIG. 10 shows an example in which the end face 47 b is located at adistance from the medium facing surface 10 a, the end face 47 b may belocated in the medium facing surface 10 a.

FIG. 11 is a perspective view showing the waveguide 47, the buffer layer46 and the near-field light generating element 44 in the vicinity of theend face 47 b. As shown in FIG. 11, the outer surface of the waveguide47 further includes a top surface 47 c, a bottom surface 47 d, and twoside surfaces 47 e and 47 f. The bottom surface 47 d is in contact withthe top surface of the buffer layer 46.

The recording head 15 further includes the overcoat layer 50 mentionedpreviously. The overcoat layer 50 is disposed on the buffer layer 46 andcovers the outer surface of the waveguide 47 excluding the incident endface 47 a and the bottom surface 47 d. Each of the buffer layer 46 andthe overcoat layer 50 is made of a dielectric material and has arefractive index lower than that of the waveguide 47. Consequently, thewaveguide 47 excluding the incident end face 47 a is covered with thedielectric material that is lower in refractive index than the waveguide47. The buffer layer 46 and the overcoat layer 50 may be made of thesame material or different materials. The buffer layer 46 and theovercoat layer 50 also function as clad layers for the waveguide 47.

As shown in FIG. 5 and FIG. 6, the slider 10 includes a conductive layer49 disposed on the top surface of the insulating layer 42 in the areawhere the laser diode 60 is to be disposed. The conductive layer 49 ismade of a conductive material, such as a metal that contains Au as amain component. The conductive layer 49 constitutes at least a part ofthe first portion 10 c 1 of the top surface 10 c of the slider 10. Thelaser diode 60 is disposed on the conductive layer 49. As shown in FIG.5, the slider 10 further includes connecting layers 82 and 84 ofcolumnar shape that electrically connect the conductive layer 49 to theterminal 54A. The connecting layer 82 is disposed on the conductivelayer 49. The connecting layer 84 is disposed on the connecting layer82. The terminal 54A is disposed on the connecting layer 84. Theconnecting layers 82 and 84 are made of Cu, for example.

Although not shown, the recording head 15 may further include a heaterfor heating the components of the recording head 15 including themagnetic pole 41 so as to control the distance between the magneticrecording medium 201 and the end face of the magnetic pole 41 located inthe medium facing surface 10 a. The heater is electrically connected tothe terminals 52A and 52B.

An example of the configuration of the laser diode 60 will now bedescribed with reference to FIG. 7. The laser diode 60 shown in FIG. 7is rectangular-solid-shaped, having a bottom surface 60 a, a top surface60 b, and four surfaces that connect the top and bottom surfaces 60 aand 60 b to each other. One of the four surfaces that connect the topand bottom surfaces 60 a and 60 b to each other is the emitting end face60 c.

The laser diode 60 includes: an n-substrate 62 having two surfaces thatface toward mutually opposite directions; an n-electrode 61 bonded toone of the two surfaces of the n-substrate 62; a laser structure part 63integrated on the other of the two surfaces of the n-substrate 62; and ap-electrode 64 bonded to the laser structure part 63 such that the laserstructure part 63 is sandwiched between the p-electrode 64 and then-substrate 62. The n-electrode 61 and the p-electrode 64 are each madeof a conductive material, such as a metal that contains Au as a maincomponent.

In the example shown in FIG. 7, the laser structure part 63 includes ann-clad layer 631, an n-guide layer 632, an active layer 633, a p-guidelayer 634, a p-clad layer 635, an n-current blocking layer 636, and ap-contact layer 637 arranged in this order as viewed from then-substrate 62. The laser structure part 63 also has a light propagationpath (waveguide channel) 633 b of stripe shape that includes a part ofthe active layer 633 and extends in a direction perpendicular to theemitting end face 60 c. The active layer 633 has a surface that facesthe n-guide layer 632 and a surface that faces the p-guide layer 634.The n-current blocking layer 636 has an opening of stripe shape thatextends in one direction. The p-clad layer 635 makes contact with thep-contact layer 637 in this opening. With such a configuration, acurrent path of stripe shape extending in one direction is formed in thelaser structure part 63. This consequently creates the light propagationpath 633 b in the laser structure part 63. In the direction parallel tothe emitting end face 60 c and the plane of the active layer 633 (the Xdirection in FIG. 7), the light propagation path 633 b has a width Wesmaller than the width W_(LA) of the laser diode 60. A laser diodehaving the light propagation path 633 b of such stripe shape is referredto as a stripe laser. Various methods are available for forming thelight propagation path 633 b of stripe shape in the stripe laser, inaddition to the foregoing method which uses the n-current blocking layer636.

The emitting end face 60 c lies at an end in the direction parallel tothe plane of the active layer 633, or more specifically at one of endsin the direction in which the current path of stripe shape extends. Theemitting end face 60 c includes an emission part 633 a that lies at anend of the light propagation path 633 b and emits laser light. From theemission part 633 a, the laser diode 60 emits polarized light of TM modewhose electric field oscillates in the direction perpendicular to theplane of the active layer 633. The laser diode 60 of the presentembodiment may be any laser diode as long as it is an edge-emittingstripe laser and emits polarized light of TM mode, and may have anyother configuration than that shown in FIG. 7.

The laser diode 60 is arranged so that the bottom surface 60 a faces thefirst portion 10 c 1 of the top surface 10 c of the slider 10. Inparticular, in the present embodiment, the laser diode 60 is arranged sothat the p-electrode 64 faces the first portion 10 c 1 of the topsurface 10 c of the slider 10. Consequently, at least a part of thebottom surface 60 a of the laser diode 60 is formed by the bottom(surface) 64 a of the p-electrode 64, and at least a part of the topsurface 60 b of the laser diode 60 is formed by the top (surface) of then-electrode 61. The bottom surface 60 a and the top surface 60 b lie atopposite ends in the direction perpendicular to the plane of the activelayer 633. The distance T_(P) between the bottom surface 60 a and theactive layer 633 is smaller than the distance T_(N) between the topsurface 60 b and the active layer 633.

FIG. 7 shows the case where the entire bottom surface 60 a is formed bythe bottom surface 64 a of the p-electrode 64, and the entire topsurface 60 b is formed by the top surface of the n-electrode 61.Nevertheless, the bottom surface 60 a may be partly formed by the bottomsurface 64 a of the p-electrode 64, and the top surface 60 b may bepartly formed by the top surface of the n-electrode 61.

The first portion 10 c 1 and the second portion 10 c 2 of the topsurface 10 c of the slider 10 have a difference in level therebetween.The difference is necessary to align the position of the emission part633 a with that of the incident end face 47 a of the waveguide 47 in theZ direction. The distance between the emission part 633 a and thesurface of the p-electrode 64 is smaller than the distance between theemission part 633 a and the surface of the n-electrode 61. This makes itpossible that, when the laser diode 60 is situated so that thep-electrode 64 faces the first portion 10 c 1 of the top surface 10 c ofthe slider 10, the difference in level between the first portion 10 c 1and the second portion 10 c 2 of the top surface 10 c of the slider 10is smaller as compared with the case where the laser diode 60 issituated so that the n-electrode 61 faces the first portion 10 c 1.

The laser diode 60 may be a laser diode of InP type, GaAs type, GaN typeor the like that is commonly used for such applications ascommunications, optical disc storage and material analysis. The laserdiode 60 may emit laser light of any wavelength within the range of, forexample, 375 nm to 1.7 μm. Specifically, the laser diode 60 may be anInGaAsP/InP quarternary mixed crystal laser diode having an emittablewavelength range of 1.2 to 1.67 μm, for example. The laser diode 60 hasa thickness T_(LA) of around 60 to 200 μm, for example.

The conductive layer 49 is in contact with and electrically connected tothe p-electrode 64. The p-electrode 64 is thereby electrically connectedto the terminal 54A via the conductive layer 49. As shown in FIG. 4, then-electrode 61 which forms the top surface 60 b of the laser diode 60 iselectrically connected to the terminal 54B with a bonding wire 68, forexample. When a voltage for driving the laser diode 60 is applied to theterminals 54A and 54B, the voltage is supplied to the laser diode 60 viathe conductive layer 49 and the bonding wire 68. Laser light is therebyemitted from the emission part 633 a of the laser diode 60.

The laser diode 60 can be driven by a power supply inside the magneticdisk drive. The magnetic disk drive usually includes a power supply thatgenerates a voltage of 2 V or so, for example. This supply voltage issufficient to drive the laser diode 60. The laser diode 60 has a powerconsumption of, for example, several tens of milliwatts or so, which canbe adequately covered by the power supply in the magnetic disk drive.

As shown in FIG. 3, the laser diode 60 is arranged so that the emittingend face 60 c is parallel to the XZ plane and the laser light emittedfrom the emission part 633 a travels in the −Y direction. The incidentend face 47 a of the waveguide 47 is opposed to the emission part 633 aof the laser diode 60. The waveguide 47 has a curved shape so that thedirection of travel of the laser light that has traveled in the −Ydirection and entered the waveguide 47 from the incident end face 47 ais turned to the −X direction.

As shown in FIG. 10, the overcoat layer 50 has an end face 50 a thatfaces the emitting end face 60 c of the laser diode 60. The emitting endface 60 c of the laser diode 60 is positioned to leave a gap from theincident end face 47 a of the waveguide 47 and the end face 50 a of theovercoat layer 50.

While FIG. 5 shows the case where the incident end face 47 a of thewaveguide 47 is exposed to form a surface continuous to the end face 50a of the overcoat layer 50, the incident end face 47 a may be thinlycovered with a part of the overcoat layer 50.

A description will now be given of the conductive layer 49 of the slider10 and the p-electrode 64 of the laser diode 60 with reference to FIG. 1and FIG. 6. FIG. 1 is a perspective view showing the conductive layer 49of the slider 10 and the laser diode 60 in a state where the laser diode60 is separated from the slider 10.

The p-electrode 64 of the laser diode 60 is bonded to the conductivelayer 49 of the slider 10. As viewed from above the laser diode 60, thebottom surface 64 a of the p-electrode 64 of the laser diode 60 includesa first area 64 a 1 that the light propagation path 633 b overlies and asecond area 64 a 2 other than the first area 64 a 1. The top surface 49a of the conductive layer 49 is in contact not with the first area 64 a1 but with the second area 64 a 2 of the bottom surface 64 a of thep-electrode 64.

In the present embodiment, in particular, the second area 64 a 2includes two portions 64 a 21 and 64 a 22 that sandwich the first area64 a 1 therebetween. The top surface 49 a of the conductive layer 49includes first and second contact surfaces 49Aa and 49Ba that makecontact with the two portions 64 a 21 and 64 a 22 of the second area 64a 2. The conductive layer 49 also has a first portion 49A that has thefirst contact surface 49Aa, and a second portion 49B that has the secondcontact surface 49Ba. As viewed from above the laser diode 60, the firstand second portions 49A and 49B are separated from each other so as tosandwich the first area 64 a 1 therebetween. As shown in FIG. 5, thefirst portion 49A extends to a position under the terminal 54A. Theconnecting layer 82 is disposed on the first portion 49A.

The relationship among the waveguide 47, the buffer layer 46 and thenear-field light generating element 44 and the principle of generationof near-field light according to the present embodiment will now bedescribed with reference to FIG. 11 and FIG. 12. FIG. 11 is aperspective view showing the waveguide 47, the buffer layer 46 and thenear-field light generating element 44. FIG. 12 is an explanatorydiagram for explaining the principle of generation of near-field lightaccording to the present embodiment.

FIG. 11 shows an example of the shape of the near-field light generatingelement 44. The near-field light generating element 44 shown in FIG. 11has a shape longer in the X direction. The outer surface of thenear-field light generating element 44 includes: a first end face 44 athat is located in the medium facing surface 10 a; a second end face 44b that is farther from the medium facing surface 10 a; and a connectingportion that connects the first end face 44 a and the second end face 44b to each other. The connecting portion includes a top surface 44 c, andtwo side surfaces 44 d and 44 e that decrease in distance from eachother with decreasing distance to the top surface 11 c of the substrate11. The top surface 44 c includes a coupling part 44 c 1 that extendsfrom a midpoint between the first end face 44 a and the second end face44 b to the second end face 44 b, and a tapered part 44 c 2 that extendsfrom the foregoing midpoint to the first end face 44 a. The couplingpart 44 c 1 is parallel to the XY plane. The tapered part 44 c 2 isinclined with respect to the XY plane such that the distance to the topsurface 11 c of the substrate 11 decreases toward the first end face 44a. Each of the first end face 44 a and the second end face 44 b isshaped like an isosceles triangle with its vertex downward. The firstend face 44 a has an area smaller than that of the second end face 44 b.In the near-field light generating element 44 shown in FIG. 11, thefirst end face 44 a constitutes a near-field light generating part thatis located in the medium facing surface 10 a and generates near-fieldlight. The bottom surface 47 d of the waveguide 47 is opposed to thecoupling part 44 c 1 of the top surface 44 c of the near-field lightgenerating element 44 with the buffer layer 46 interposed therebetween.

The maximum width W_(NF) (see FIG. 11) of the near-field lightgenerating element 44 in the track width direction (Y direction) and themaximum thickness (dimension in the Z direction) T_(NF) (see FIG. 12) ofthe near-field light generating element 44 are both sufficiently smallerthan the wavelength of laser light 71 (see FIG. 12) that is emitted fromthe laser diode 60 and propagates through the waveguide 47. W_(NF) fallswithin the range of 100 to 300 nm, for example. TNF falls within therange of 60 to 150 nm, for example. The near-field light generatingelement 44 has a length H_(NF) (see FIG. 12) in the X direction of, forexample, 0.5 to 3 μm.

In the vicinity of the near-field light generating element 44, thewaveguide 47 has a width W_(WG) (see FIG. 11) in the track widthdirection (Y direction) of, for example, 0.3 to 1 μm. In the vicinity ofthe near-field light generating element 44, the waveguide 47 has athickness (dimension in the Z direction) T_(WG) (see FIG. 12) of, forexample, 0.1 to 1 μm. The distance D_(BF) between the end face 47 b ofthe waveguide 47 and the medium facing surface 10 a falls within therange of 0 to 2.0 μm, for example.

As shown in FIG. 12, the distance between the bottom surface 47 d of thewaveguide 47 and the coupling part 44 c 1 of the near-field lightgenerating element 44 that are opposed to each other with the bufferlayer 46 therebetween will be denoted by the symbol BT. The distance BTfalls within the range of 20 to 100 nm, for example. The length of thecoupling part 44 c 1 will be denoted by BL. The length BL falls withinthe range of 0.5 to 3 μm, for example.

As described previously, each of the buffer layer 46 and the overcoatlayer 50 has a refractive index lower than that of the waveguide 47. Thebuffer layer 46 and the overcoat layer 50 may be made of the samematerial or different materials. For example, if the wavelength of thelaser light 71 is 600 nm and the waveguide 47 is made of Al₂O₃(refractive index n=1.63), the buffer layer 46 and the overcoat layer 50may be made of SiO₂ (refractive index n=1.46). If the waveguide 47 ismade of tantalum oxide such as Ta₂O₅ (n=2.16), the buffer layer 46 andthe overcoat layer 50 may be made of SiO₂ (n=1.46) or Al₂O₃ (n=1.63).

Reference is now made to FIG. 12 to describe the principle of generationof near-field light and the principle of heat-assisted magneticrecording using the near-field light. The laser light 71 emitted fromthe laser diode 60 propagates through the waveguide 47 to reach thevicinity of the buffer layer 46. The laser light 71 propagating throughthe waveguide 47 is TM-polarized light whose electric field oscillatesin the direction perpendicular to the top surface 47 c and the bottomsurface 47 d of the waveguide 47. Here, the laser light is totallyreflected at the interface between the waveguide 47 and the buffer layer46, and this generates evanescent light permeating into the buffer layer46. Then, this evanescent light and fluctuations of charges on thecoupling part 44 c 1 of the top surface 44 c of the near-field lightgenerating element 44 are coupled with each other to induce a surfaceplasmon polariton mode, whereby surface plasmons 72 are excited on thecoupling part 44 c 1.

The surface plasmons 72 excited on the coupling part 44 c 1 propagatealong the tapered part 44 c 2 of the top surface 44 c of the near-fieldlight generating element 44 to reach the near-field light generatingpart (the end face 44 a). As a result, the surface plasmons 72concentrate at the near-field light generating part (the end face 44 a),and near-field light 73 thus occurs from the near-field light generatingpart (the end face 44 a) based on the surface plasmons 72. Thenear-field light 73 is projected toward the magnetic disk 201, reachesthe surface of the magnetic disk 201, and heats a part of the magneticrecording layer of the magnetic disk 201. This lowers the coercivity ofthe part of the magnetic recording layer. In heat-assisted magneticrecording, the part of the magnetic recording layer with the loweredcoercivity is subjected to a recording magnetic field produced by themagnetic pole 41 for data recording.

The heat-assisted magnetic recording head 1 according to the presentembodiment is capable of converting the laser light that propagatesthrough the waveguide 47 into near-field light with higher light useefficiency, compared with the case where near-field light is generatedfrom a plasmon antenna by directly irradiating the plasmon antenna withlaser light. Consequently, according to the present embodiment, it ispossible to prevent a part of the medium facing surface 10 a fromprotruding due to conversion of the energy of the laser light intothermal energy in the heat-assisted magnetic recording head 1.

It should be noted that possible shapes of the near-field lightgenerating element 44 are not limited to the one shown in FIG. 11. Forexample, the near-field light generating element 44 may betetragonal-prism-shaped. In this case, the cross section of thenear-field light generating element 44 parallel to the medium facingsurface 10 a may be rectangular, or may be trapezoidal such that thewidth decreases with decreasing distance to the top surface 11 c of thesubstrate 11.

Reference is now made to FIG. 13 to describe the circuit configurationof the control circuit 230 shown in FIG. 8 and the operation of theheat-assisted magnetic recording head 1. The control circuit 230includes a control LSI (large scale integrated circuit) 100, a ROM (readonly memory) 101 connected to the control LSI 100, a write gate 111connected to the control LSI 100, and a write circuit 112 connected tothe write gate 111 and the coil 37.

The control circuit 230 further includes a constant current circuit 121connected to the MR element 22 and the control LSI 100, an amplifier 122connected to the MR element 22, and a demodulator circuit 123 connectedto an output of the amplifier 122 and the control LSI 100.

The control circuit 230 further includes a laser control circuit 131connected to the laser diode 60 and the control LSI 100, and atemperature detector 132 connected to the control LSI 100.

The control LSI 100 supplies recording data and a recording controlsignal to the write gate 111. The control LSI 100 supplies areproduction control signal to the constant current circuit 121 and thedemodulator circuit 123, and receives reproduced data output from thedemodulator circuit 123. The control LSI 100 supplies a laser ON/OFFsignal and an operating current control signal to the laser controlcircuit 131. The temperature detector 132 detects the temperature of themagnetic recording layer of the magnetic disk 201, and supplies thistemperature information to the control LSI 100. The ROM 101 contains acontrol table and the like for controlling the value of the operatingcurrent to be supplied to the laser diode 60.

In a recording operation, the control LSI 100 supplies recording data tothe write gate 111. The write gate 111 supplies the recording data tothe write circuit 112 only when the recording control signal indicates arecording operation. According to the recording data, the write circuit112 passes a recording current through the coil 37. Consequently, themagnetic pole 41 produces a recording magnetic field and data isrecorded on the magnetic recording layer of the magnetic disk 201through the use of this recording magnetic field.

In a reproducing operation, the constant current circuit 121 supplies acertain sense current to the MR element 22 only when the reproductioncontrol signal indicates a reproducing operation. The output voltage ofthe MR element 22 is amplified by the amplifier 122 and input to thedemodulator circuit 123. When the reproduction control signal indicatesa reproducing operation, the demodulator circuit 123 demodulates theoutput of the amplifier 122 to generate reproduced data, and suppliesthe reproduced data to the control LSI 100.

The laser control circuit 131 controls the supply of the operatingcurrent to the laser diode 60 on the basis of the laser ON/OFF signal,and also controls the value of the operating current to be supplied tothe laser diode 60 on the basis of the operating current control signal.When the laser ON/OFF signal indicates an ON operation, the lasercontrol circuit 131 exercises control so that an operating current at orabove an oscillation threshold is supplied to the laser diode 60.Consequently, the laser diode 60 emits laser light, and the laser lightpropagates through the waveguide 47. According to the principle ofgeneration of near-field light described above, the near-field light 73occurs from the near-field light generating part (the end face 44 a) ofthe near-field light generating element 44. The near-field light 73heats a part of the magnetic recording layer of the magnetic disk 201,thereby lowering the coercivity of that part. When recording, the partof the magnetic recording layer with the lowered coercivity is subjectedto the recording magnetic field produced by the magnetic pole 41 fordata recording.

On the basis of such factors as the temperature of the magneticrecording layer of the magnetic disk 201 measured by the temperaturedetector 132, the control LSI 100 consults the control table stored inthe ROM 101 to determine the value of the operating current for thelaser diode 60. Using the operating current control signal, the controlLSI 100 controls the laser control circuit 131 so that the operatingcurrent of that value is supplied to the laser diode 60. The controltable contains, for example, data that indicates the oscillationthreshold and the temperature dependence of the light output versusoperating current characteristic of the laser diode 60. The controltable may further contain data that indicates the relationship betweenthe operating current value and a temperature increase of the magneticrecording layer heated by the near-field light 73, and data thatindicates the temperature dependence of the coercivity of the magneticrecording layer.

As shown in FIG. 13, the control circuit 230 has the signal system forcontrolling the laser diode 60, i.e., the signal system consisting ofthe laser ON/OFF signal and the operating current control signal,independent of the control signal system intended forrecording/reproducing operations. This configuration makes it possibleto implement various modes of energization of the laser diode 60, notonly to energize the laser diode 60 simply in association with arecording operation. It should be noted that possible circuitconfigurations of the control circuit 230 are not limited to the oneshown in FIG. 13.

A description will now be given of a manufacturing method for theheat-assisted magnetic recording head 1 according to the presentembodiment. The manufacturing method for the heat-assisted magneticrecording head 1 according to the present embodiment includes the stepof fabricating the slider 10 and the step of fixing the laser diode 60to the slider 10.

In the step of fabricating the slider 10, the slider 10 is completed bystacking the plurality of components of the head unit 12 on the topsurface 11 c of the substrate 11. Reference is now made to FIG. 14 toFIG. 24 to describe a method of forming the waveguide 47, the conductivelayer 49 and the overcoat layer 50 and a method of installing the laserdiode 60 of the present embodiment. FIG. 14 to FIG. 24 arecross-sectional views each showing a part of a stack of layers formed inthe process of manufacturing the heat-assisted magnetic recording head1. Each of FIG. 14 to FIG. 24 shows a cross section corresponding toFIG. 5.

FIG. 14 shows the step after the formation of the magnetic pole 41 andthe insulating layer 42 in the process of manufacturing theheat-assisted magnetic recording head 1. In this step, the conductivelayer 49 patterned is formed on the insulating layer 42. Of theconductive layer 49, only the first portion 49A is shown in FIG. 14 toFIG. 24.

FIG. 15 shows the next step. This step forms a sacrificial layer 81 andthe connecting layer 82 that are patterned. The sacrificial layer 81 islocated in the area where to form the first portion 10 c 1 of the topsurface 10 c of the slider 10. The sacrificial layer 81 is made ofalumina, SiO₂, or photoresist, for example.

FIG. 16 shows the next step. In this step, first, the insulating layer43 is formed over the entire top surface of the stack shown in FIG. 15.Next, the near-field light generating element 44 (not shown in FIG. 16)and the insulating layer 45 are formed on the insulating layer 43.

FIG. 17 shows the next step. In this step, chemical mechanical polishing(hereinafter, referred to as CMP), for example, is performed to polishand flatten the top surfaces of the insulating layer 43, the near-fieldlight generating element 44 (not shown in FIG. 17), the insulating layer45, the sacrificial layer 81, and the connecting layer 82. To create thenear-field light generating element 44 that has the top surface 44 cincluding the tapered part 44 c 2 as shown in FIG. 11, the layer to bemade into the near-field light generating element 44 is flattened at thetop by polishing, and then a part of the layer is taper-etched to formthe tapered part 44 c 2.

FIG. 18 shows the next step. In this step, first, the buffer layer 46 isformed on the top surface of the stack shown in FIG. 17, over the areasexcluding the top surfaces of the sacrificial layer 81 and theconnecting layer 82. Next, the waveguide 47 patterned is formed on thebuffer layer 46.

FIG. 19 shows the next step. In this step, a sacrificial layer 83patterned is formed on the sacrificial layer 81, and the connectinglayer 84 patterned is formed on the connecting layer 82. The sacrificiallayer 83 is made of alumina, SiO₂, or photoresist, for example.

Next, as shown in FIG. 20, the overcoat layer 50 is formed over theentire top surface of the stack shown in FIG. 19. Next, as shown in FIG.21, the overcoat layer 50 is polished by, for example, CMP, until thesacrificial layer 83 and the connecting layer 84 are exposed.

FIG. 22 shows the next step. In this step, the terminals 51A, 51B, 52A,52B, 53A, 53B, 54A and 54B are formed on the overcoat layer 50. FIG. 22shows the terminals 54A and 54B only. The terminal 54A is disposed onthe connecting layer 84. Next, as shown in FIG. 23, the sacrificiallayers 81 and 83 are removed by wet etching. The conductive layer 49 isthereby exposed.

FIG. 24 shows the next step. In this step, first, the laser diode 60 isplaced in the area where the sacrificial layers 81 and 83 have beenremoved. The laser diode 60 is then fixed to the slider 10.Specifically, the laser diode 60 is fixed to the slider 10 by bondingthe p-electrode 64 of the laser diode 60 to the conductive layer 49.Next, the n-electrode 61 of the laser diode 60 is electrically connectedto the terminal 54B with the bonding wire 68, for example.

Note that FIG. 24 shows the case where the incident end face 47 a of thewaveguide 47 is thinly covered with a part of the overcoat layer 50.This configuration can be achieved by forming the sacrificial layer 83so as to leave a gap between the incident end face 47 a of the waveguide47 and the side surface of the sacrificial layer 83 as shown in FIG. 19.If the sacrificial layer 83 is formed so that its side surface is incontact with the incident end face 47 a in the step shown in FIG. 19,then the incident end face 47 a will be exposed to form a surfacecontinuous to the end face 50 a of the overcoat layer 50 as shown inFIG. 5.

The step of fixing the laser diode 60 to the slider 10 will now bedescribed in detail with reference to FIG. 1, FIG. 2, and FIG. 6. FIG. 2is an explanatory diagram for explaining the step of fixing the laserdiode 60 to the slider 10. In this step, the p-electrode 64 is bonded tothe conductive layer 49 by ultrasonic bonding wherein ultrasonicvibrations are applied to the laser diode 60 in the directionperpendicular to the emitting end face 60 c, with the second area 64 a 2of the bottom surface 64 a of the p-electrode 64 in contact with the topsurface 49 a of the conductive layer 49, as shown in FIG. 6. In FIG. 1,the arrow designated by the reference numeral 70 shows the direction ofthe ultrasonic vibrations to be applied to the laser diode 60. Theultrasonic bonding causes solid-phase diffusion between the conductivelayer 49 and the p-electrode 64, whereby the conductive layer 49 and thep-electrode 64 are bonded to each other.

This step can be performed, for example, by using an ultrasonic bondingapparatus 300 shown in FIG. 2. The ultrasonic bonding apparatus 300shown in FIG. 2 is a typical ultrasonic flip chip bonder that is used toflip-chip bond a chip to a substrate by ultrasonic bonding.

The ultrasonic bonding apparatus 300 includes a substrate stage 301, abonding head 310, cameras 302 and 303, and a pressure device 305. Thebonding head 310 is provided over the substrate stage 301 so as to bemovable in horizontal and vertical directions.

The bonding head 310 includes an ultrasonic horn 311, an ultrasonicvibrator 312, and a bonding tool 313. The ultrasonic vibrator 312 isconnected to an end of the ultrasonic horn 311. The bonding tool 313 isconnected to the ultrasonic horn 311 in the vicinity of the other end ofthe ultrasonic horn 311 so as to protrude downward from the bottom ofthe ultrasonic horn 311. The bonding tool 313 has a suction surface 313a for sucking a component to be bonded. The bonding tool 313 isconfigured to be capable of holding the component to be bonded bysucking it to the suction surface 313 a.

The ultrasonic horn 311 is driven by the ultrasonic vibrator 312 togenerate ultrasonic vibrations in the direction of the arrow shown bythe reference numeral 321. The bonding tool 313 is thus vibrated in thedirection of the arrow shown by the reference numeral 322. Thevibrations of the bonding tool 313 are applied to the component to bebonded.

The camera 302 is used to detect the position of the component to bebonded that is held by the bonding tool 313. The camera 303 is used todetect the position of the substrate that is placed on the substratestage 301. The pressure device 305 applies pressure to the ultrasonichorn 311 and the bonding tool 313 downward.

To fix the laser diode 60 to the slider 10 by using the ultrasonicbonding apparatus 300 shown in FIG. 2, the slider 10 is initially placedon and fixed to the substrate stage 301 with the top surface 10 cupward. Next, the laser diode 60 is held by the bonding tool 313 withthe bottom surface 60 a downward. The bonding tool 313 is then moved sothat the laser diode 60 is located at a desired position on the firstportion 10 c 1 of the top surface 10 c of the slider 10. This brings thesecond area 64 a 2 of the bottom surface 64 a of the p-electrode 64 intocontact with the top surface 49 a of the conductive layer 49 as shown inFIG. 6. The slider 10 and the laser diode 60 can be aligned based on theposition information on the slider 10 and the laser diode 60 detected byusing the cameras 302 and 303. With the second area 64 a 2 of the bottomsurface 64 a of the p-electrode 64 in contact with the top surface 49 aof the conductive layer 49, the pressure device 305 then appliespressure to the ultrasonic horn 311 and the bonding tool 313 downwardwhile the bonding tool 313 applies ultrasonic vibrations to the laserdiode 60 in the direction perpendicular to the emitting end face 60 c.The p-electrode 64 is thus bonded to the conductive layer 49 byultrasonic bonding. Note that the ultrasonic bonding apparatus for usein fixing the laser diode 60 to the slider 10 may have any otherconfiguration than that shown in FIG. 2.

As has been described, in the heat-assisted magnetic recording head 1according to the present embodiment, the edge-emitting laser diode 60 isfixed to the slider 10 such that the bottom surface 60 a lying at an endin the direction perpendicular to the plane of the active layer 633faces the top surface 10 c of the slider 10. This makes it possible toalign the position of the emission part 633 a with respect to theincident end face 47 a of the waveguide 47 in the Z direction easilywith high precision. Consequently, according to the present embodiment,it is easy to align the emission part 633 a with respect to the incidentend face 47 a of the waveguide 47 while using the edge-emitting laserdiode 60 which has a high optical output.

In the present embodiment, the laser diode 60 is arranged so that thep-electrode 64 faces the first portion 10 c 1 of the top surface 10 c ofthe slider 10. This makes it possible to reduce the difference in levelbetween the first portion 10 c 1 and the second portion 10 c 2 of thetop surface 10 c of the slider 10 as compared with the case where thelaser diode 60 is arranged so that the n-electrode 61 faces the firstportion 10 c 1, as mentioned previously. According to the presentembodiment, the active layer 633, which generates heat when the laserdiode 60 is in operation, can be located closer to the substrate 11 thanin the case where the laser diode 60 is arranged so that the n-electrode61 faces the first portion 10 c 1. This can promote heat dissipationfrom the laser diode 60.

With the laser diode 60 which emits polarized light of TM mode, thestate of polarization of the emitted light changes sensitively inresponse to the stress that acts on the active layer 633, or the portionthereof constituting the light propagation path 633 b in particular. Inthe present embodiment, as viewed from above the laser diode 60, thebottom surface 64 a of the p-electrode 64 of the laser diode 60 includesthe first area 64 a 1 that the light propagation path 633 b of the laserdiode 60 overlies and the second area 64 a 2 other than the first area64 a 1. The top surface 49 a of the conductive layer 49 is in contactnot with the first area 64 a 1 but with the second area 64 a 2 of thebottom surface 64 a of the p-electrode 64. According to the presentembodiment, it is thus possible to prevent a stress resulting from thebonding between the p-electrode 64 and the conductive layer 49 fromacting on the light propagation path 633 b. Consequently, according tothe present embodiment, it is possible to suppress changes in the stateof polarization of the light emitted from the laser diode 60.

In the present embodiment, the p-electrode 64 is bonded to theconductive layer 49 by ultrasonic bonding in the step of fixing thelaser diode 60 to the slider 10. In the ultrasonic bonding, ultrasonicvibrations are applied to the laser diode 60 in the directionperpendicular to the emitting end face 60 c, with the second area 64 a 2of the bottom surface 64 a of the p-electrode 64 in contact with the topsurface 49 a of the conductive layer 49. According to the presentembodiment, it is possible to reduce the stress occurring from thebonding between the p-electrode 64 and the conductive layer 49, ascompared with the case where the p-electrode 64 is bonded to theconductive layer 49 by soldering. In this respect also, the presentembodiment makes it possible to prevent a stress resulting from thebonding between the p-electrode 64 and the conductive layer 49 fromacting on the light propagation path 633 b, and thereby makes itpossible to suppress changes in the state of polarization of the lightemitted from the laser diode 60.

If the emission part 633 a of the laser diode 60 is misaligned withrespect to the incident end face 47 a of the waveguide 47 in a directionparallel to the emitting end face 60 c, the amount of laser light thatenters the waveguide 47 decreases. This can cause a drop in theintensity of the laser light to be used for generating near-field light.In the present embodiment, ultrasonic vibrations are applied to thelaser diode 60 in the direction perpendicular to the emitting end face60 c in the ultrasonic bonding. The present embodiment thus makes itpossible to prevent the emission part 633 a of the laser diode 60 frombeing misaligned with respect to the incident end face 47a of thewaveguide 47 in a direction parallel to the emitting end face 60 cduring the ultrasonic bonding.

Consequently, according to the present embodiment, it is possible toprevent a drop in the intensity of the laser light to be used forgenerating near-field light. It should be noted that the application ofultrasonic vibrations to the laser diode 60 in the directionperpendicular to the emitting end face 60 c may cause a misalignment ofthe emission part 633 a with respect to the incident end face 47 a ofthe waveguide 47 in the direction perpendicular to the emitting end face60 c. In such a case, however, there occurs hardly any change in theamount of the laser light that enters the waveguide 47.

[Second Embodiment]

A second embodiment of the present invention will now be described withreference to FIG. 25. FIG. 25 is a cross-sectional view showing a partof the heat-assisted magnetic recording head 1 according to the presentembodiment. FIG. 25 shows a cross section taken at the same position asin FIG. 6.

In the present embodiment, the insulating layer 42 disposed under theconductive layer 49 has a recess 42 a in its top surface. The recess 42a is opposed to the first area 64 a 1 of the bottom surface 64 a of thep-electrode 64 of the laser diode 60. The conductive layer 49 of thepresent embodiment includes a third portion 49C that is recessed alongthe recess 42 a so as not to make contact with the first area 64 a 1. Inthe present embodiment, the first portion 49A and the second portion 49Bof the conductive layer 49 are connected by the third portion 49C, notbeing separated from each other. The top surface 49 a of the conductivelayer 49 includes first and second contact surfaces 49Aa and 49Ba thatmake contact with the two portions 64 a 21 and 64 a 22 of the secondarea 64 a 2, and a non-contact surface 49Ca that lies between the firstand second contact surfaces 49Aa and 49Ba. The non-contact surface 49Cais the top surface of the third portion 49C, and is not in contact withthe bottom surface 64 a of the p-electrode 64.

As compared with the step of fabricating the slider 10 of the firstembodiment, the step of fabricating the slider 10 of the presentembodiment includes an additional step of forming the recess 42 a in thetop surface of the insulating layer 42 by etching.

The remainder of configuration, function and effects of the presentembodiment are similar to those of the first embodiment.

It should be appreciated that the present invention is not limited tothe foregoing embodiments, and various modifications may be madethereto. For example, the foregoing embodiments have dealt with thecases where the waveguide 47, the buffer layer 46 and the near-fieldlight generating element 44 are arranged so that the near-field lightgenerating element 44 is opposed to the bottom surface of the waveguide47 with the buffer layer 46 interposed therebetween in the vicinity ofthe medium facing surface 10 a. The waveguide 47, the buffer layer 46and the near-field light generating element 44, however, may be arrangedso that the near-field light generating element 44 is opposed to the topsurface of the waveguide 47 with the buffer layer 46 interposedtherebetween in the vicinity of the medium facing surface 10 a. In thiscase also, the laser light to propagate through the waveguide 47 needsto be TM-polarized.

In the foregoing embodiments, the end face 44 a of the near-field lightgenerating element 44 is located in the medium facing surface 10 a at aposition forward of the end face of the magnetic pole 41 along the Zdirection (in other words, located closer to the trailing end). However,the end face 44 a of the near-field light generating element 44 may belocated backward of the end face of the magnetic pole 41 along the Zdirection (in other words, located closer to the leading end) in themedium facing surface 10 a.

It is apparent that the present invention can be carried out in variousforms and modifications in the light of the foregoing descriptions.Accordingly, within the scope of the following claims and equivalentsthereof, the present invention can be carried out in forms other thanthe foregoing most preferable embodiment.

1. A heat-assisted magnetic recording head comprising a slider, and anedge-emitting laser diode fixed to the slider, the slider comprising: amedium facing surface that faces a magnetic recording medium; a magneticpole that has an end face located in the medium facing surface andproduces a recording magnetic field for recording data on the magneticrecording medium; a waveguide that allows light to propagatetherethrough; a near-field light generating element that generatesnear-field light; and a substrate on which the magnetic pole, thenear-field light generating element and the waveguide are stacked,wherein: the substrate has a top surface facing toward the magneticpole, the near-field light generating element and the waveguide; theslider has a top surface that lies at an end above the top surface ofthe substrate; the laser diode includes: an active layer; an emittingend face that lies at an end in a direction parallel to a plane of theactive layer and includes an emission part for emitting laser light; alight propagation path that includes a part of the active layer andextends in a direction perpendicular to the emitting end face; a bottomsurface and a top surface that lie at opposite ends in a directionperpendicular to the plane of the active layer; and an electrode havinga bottom surface that constitutes at least a part of the bottom surfaceof the laser diode, the laser diode being arranged so that the bottomsurface of the laser diode faces the top surface of the slider; thelight propagation path has a width smaller than that of the laser diodein a direction parallel to the emitting end face and the plane of theactive layer; a distance between the bottom surface of the laser diodeand the active layer is smaller than that between the top surface of thelaser diode and the active layer; the laser light emitted from theemission part is polarized light of TM mode whose electric fieldoscillates in the direction perpendicular to the plane of the activelayer; the waveguide has an outer surface, the outer surface includingan incident end face that is opposed to the emission part of the laserdiode; the near-field light generating element has a near-field lightgenerating part that is located in the medium facing surface, and acoupling part that is opposed to the outer surface of the waveguide, asurface plasmon being excited on the coupling part based on the lightpropagating through the waveguide, the surface plasmon propagating tothe near-field light generating part, the near-field light generatingpart generating near-field light based on the surface plasmon; theslider further comprises a conductive layer having a top surface thatconstitutes a part of the top surface of the slider; the electrode ofthe laser diode is bonded to the conductive layer of the slider; asviewed from above the laser diode, the bottom surface of the electrodeof the laser diode includes a first area that the light propagation pathoverlies, and a second area other than the first area; and the topsurface of the conductive layer is in contact not with the first areabut with the second area of the bottom surface of the electrode.
 2. Theheat-assisted magnetic recording head according to claim 1, wherein: thesecond area includes two portions that sandwich the first areatherebetween; and the top surface of the conductive layer includes afirst contact surface and a second contact surface that make contactwith the two portions of the second area.
 3. The heat-assisted magneticrecording head according to claim 2, wherein the conductive layer has afirst portion having the first contact surface and a second portionhaving the second contact surface, the first and second portions beingseparated from each other.
 4. The heat-assisted magnetic recording headaccording to claim 2, wherein: the slider includes an insulating layerdisposed under the conductive layer; the insulating layer has a topsurface, the top surface of the insulating layer having a recess that isopposed to the first area of the bottom surface of the electrode; andthe conductive layer includes a portion that is recessed along therecess of the top surface of the insulating layer so as not to makecontact with the first area.
 5. The heat-assisted magnetic recordinghead according to claim 1, wherein: the slider further comprises abuffer layer that has a refractive index lower than that of thewaveguide and is interposed between the coupling part and the outersurface of the waveguide; and a surface plasmon is excited on thecoupling part through coupling with evanescent light that occurs from aninterface between the waveguide and the buffer layer.
 6. Theheat-assisted magnetic recording head according to claim 1, wherein eachof the electrode and the conductive layer is made of a metal thatcontains Au as a main component.
 7. The heat-assisted magnetic recordinghead according to claim 1, wherein the emitting end face of the laserdiode is positioned to leave a gap from the incident end face of thewaveguide.
 8. A manufacturing method for the heat-assisted magneticrecording head according to claim 1, comprising the steps of:fabricating the slider; and fixing the laser diode to the slider,wherein in the step of fixing the laser diode to the slider, theelectrode of the laser diode is bonded to the conductive layer of theslider by ultrasonic bonding wherein ultrasonic vibrations are appliedto the laser diode in the direction perpendicular to the emitting endface, with the second area of the bottom surface of the electrode incontact with the top surface of the conductive layer.
 9. Themanufacturing method according to claim 8, wherein: the second areaincludes two portions that sandwich the first area therebetween; and thetop surface of the conductive layer includes a first contact surface anda second contact surface that make contact with the two portions of thesecond area.
 10. The manufacturing method according to claim 9, wherein:the conductive layer has a first portion having the first contactsurface and a second portion having the second contact surface, thefirst and second portions being separated from each other.
 11. Themanufacturing method according to claim 9, wherein: the slider includesan insulating layer disposed under the conductive layer; the insulatinglayer has a top surface, the top surface of the insulating layer havinga recess that is opposed to the first area of the bottom surface of theelectrode; and the conductive layer includes a portion that is recessedalong the recess of the top surface of the insulating layer so as not tomake contact with the first area.
 12. The manufacturing method accordingto claim 8, wherein: the slider further comprises a buffer layer thathas a refractive index lower than that of the waveguide and isinterposed between the coupling part and the outer surface of thewaveguide; and a surface plasmon is excited on the coupling part throughcoupling with evanescent light that occurs from an interface between thewaveguide and the buffer layer.
 13. The manufacturing method accordingto claim 8, wherein each of the electrode and the conductive layer ismade of a metal that contains Au as a main component.
 14. Themanufacturing method according to claim 8, wherein the emitting end faceof the laser diode is positioned to leave a gap from the incident endface of the waveguide.
 15. A head gimbal assembly comprising: theheat-assisted magnetic recording head according to claim 1; and asuspension that supports the heat-assisted magnetic recording head. 16.A magnetic recording device comprising: a magnetic recording medium; theheat-assisted magnetic recording head according to claim 1; and apositioning device that supports the heat-assisted magnetic recordinghead and positions the heat-assisted magnetic recording head withrespect to the magnetic recording medium.